A small bowel (intestinal) transplant is an operation to replace a diseased or shortened small bowel with a healthy bowel from a donor.

It's a complicated and highly specialised operation that's only done at four specialist centres in the UK:

• Birmingham Children's Hospital
• Addenbrooke's Hospital in Cambridge
• Churchill Hospital in Oxford
• King's College Hospital in London

A successful small bowel transplant can allow you to live as normal a life as possible, although medicine and regular check-ups will be needed indefinitely.

When a small bowel transplant is needed

A small bowel transplant may be considered for people with bowel failure who develop complications from total parenteral nutrition (TPN), or if TPN is not possible.

TPN is where a person requires all their nutrition to be given through a drip into a vein because their bowel is unable to absorb nutrients from any food they eat.

Bowel or intestinal failure means a person's bowel is not able to absorb enough nutrients from food. It's most often caused by either short bowel syndrome or a non-functioning bowel.

Short bowel syndrome

Short bowel syndrome is where a large part of the small bowel is missing, removed or damaged.

It can be caused by:

• twisting of the bowel (volvulus)
• a birth defect where some of a baby's bowel develops outside the body (gastroschisis)
• when part of the tissue of the bowel dies (necrotising enterocolitis)
• surgery to remove a large section of bowel to treat Crohn's disease or bowel cancer

Most people with short bowel syndrome need some total parenteral nutrition (TPN). In many cases this can be given at home without causing any significant problems.

However, long-term TPN can sometimes lead to complications, which can be life threatening.

These problems include:

• running out of suitable veins to insert a catheter
• an infection where the catheter is inserted, which can spread through the bloodstream and lead to sepsis
• liver disease

Transplant assessment

If you're being considered for a small bowel transplant, you'll be referred for a transplant assessment. Tests will be done over a period of 1 to 3 weeks to see whether a transplant is the best treatment for you.

Depending on your overall health, you may need to stay in hospital while these tests are done, or you may only need to go to hospital for a series of outpatient appointments.

Tests you may have include:

• blood tests to check your liver function, electrolytes, kidney function and see if you have any serious infections, such as HIV or hepatitis
• a number of scans, such as a chest X-ray, a CT scan of your tummy (abdomen) and an ultrasound scan of your liver
• a colonoscopy, where a long, thin, flexible tube with a small camera inside it is passed into your bottom to check inside your bowels
• lung function tests

During the assessment, you'll have the chance to meet members of the transplant team and ask questions.

The transplant co-ordinator will talk to you and your family about what happens, as well as the risks involved in a small bowel transplant.

When the assessment is complete, a decision will be made about whether a small bowel transplant is the best option for you.

It may be unsuitable if:

• you have cancer that has spread to several areas of your body
• you have a serious illness with a very poor outlook
• you require breathing support with a ventilator – a machine that moves oxygen-enriched air in and out of your lungs
• you're over 60 years of age
• you have not acted on your doctor's advice (to quit smoking, for example), you have not taken the medicine prescribed to you, or you've missed hospital appointments

Waiting for a small bowel transplant

If you're suitable for a small bowel transplant and are unable to receive a living donation from a family member, you'll be placed on the national waiting list.

If you're on the waiting list, the transplant centre will need to contact you at short notice as soon as an organ becomes available for transplantation, so you must inform staff if there are any changes to your contact details.

You'll usually be contacted before the transplant surgeons have had a chance to assess the suitability of the donated organs, which means there's a chance you may be called in several times for "false alarms" before the operation is eventually done.

The length of time you wait depends on:

• your blood group
• donor availability
• how many other patients are on the list and how urgent their cases are

On average, people wait around 2 months for a small bowel transplant.

While you wait, you'll be cared for by the doctor who referred you to the transplant centre.

Your doctor will keep the transplant team updated about changes to your condition. Another assessment is sometimes necessary to make sure you're still suitable for a transplant.

Types of transplant procedures

There are three main types of transplant procedures:

• small bowel transplant only – this is recommended for people with bowel failure who do not have liver disease
• combined liver and small bowel transplant – this is recommended for people with bowel failure who also have advanced liver disease
• multiple organ (multivisceral) transplant – although it's not often done, this may be recommended for people with multiple organ failure and involves transplanting the stomach, pancreas, duodenum (the first section of small bowel), liver and small bowel

It's sometimes possible to do a small bowel transplant using a section of bowel donated by a living family member.

In these cases, the donor will need to have an operation, where the donated part of bowel is removed and the remaining sections of bowel are connected together.

How a small bowel transplant is performed

A small bowel transplant is done under general anaesthetic and takes around 8 to 10 hours to complete, although it can take longer.

After removing your diseased bowel, your blood vessels are connected to the blood vessels of the transplanted bowel. The transplanted bowel is then connected to your digestive tract or what is left of the bowel.

Your surgeon will form an ileostomy, where a part of the small bowel is diverted through an opening they make in your abdomen, called a stoma.

After the operation, the ileostomy allows digestive waste to pass out of your body through the stoma into an external pouch. It also lets the transplant team assess the health of your transplanted bowel.

Depending on your health and the operation's success, your bowel may be reconnected and the ileostomy closed a few months after the transplant, but this is not always possible.

Recovery in hospital

Immediately after a small bowel transplant you'll be taken to the intensive care unit (ICU) and carefully monitored. This is so the transplant team can check your body is accepting the new organ.

While in the ICU, you'll have various tubes in your veins to provide medicines and fluids, and you'll be attached to monitoring equipment.

You may also have regular bowel biopsies, where small samples of tissue are taken for testing, using the ileostomy created by the surgeon.

Alternatively, you may have an endoscopy, where a long, thin tube with a camera on the end is inserted into the stoma to examine the inside of your bowel.

The transplant team can determine whether your body is rejecting the donor bowel from your biopsy results. If it is, you'll be given extra treatment with medicines to suppress your immune system (immunosuppressants).

Once you've started to recover, you'll usually be transferred to a specialist transplant ward where you'll continue to be given painkillers, immunosuppressant medicine and nutrition through a tube into a vein (TPN).

Over time, the majority of people are able to move on from TPN to eating a normal diet fed through the mouth.

Recovery at home

On average, people who have a small bowel transplant are discharged from hospital after around 4 to 6 weeks.

If you live a long distance from the hospital, you may need to stay in accommodation provided by the hospital nearby, for 1 to 2 months after you are discharged, so you can be monitored and treated quickly if any problems develop.

You'll be given immunosuppressant medicine to help prevent your body rejecting the transplant. You will need to take this medicine for the rest of your life.

For the first few weeks or months after leaving hospital you'll need to continue having regular blood tests and endoscopies, but these will be done less often over time. Eventually you may only need to see your surgeon once a year and have blood tests every few months.

Although it can take a long time to make a full recovery from a small bowel transplant, and there's a risk of potentially serious complications, the aim of the operation is to allow you to eventually live as normal a life as possible – including working, enjoying hobbies and living independently.

Risks of a small bowel transplant

As with all types of surgery, there are risks associated with having a small bowel transplant.

Better anti-rejection medicines, refined surgical procedures and a greater understanding of the body's immune system have increased the number of successful bowel transplants and improved survival rates in recent years.

However, potentially serious complications can still happen:

• heart and breathing problems
• infection of the small bowel – such as an infection by the cytomegalovirus (CMV)
• blood clots (thrombosis)
• post-transplant lymphoproliferative disorder (PTLD) – where the Epstein-Barr virus infects white blood cells, which can lead to abnormal growths throughout the body and multiple organ failure, if not treated quickly
• rejection of the donor organ
• problems associated with the long-term use of anti-rejection medication – such as an increased risk of infections, kidney problems and certain types of cancer

Because of these risks and the overall poor health of people who are considered for a small bowel transplant, some people die within a few years of the procedure.

However, the majority of adults and children who have the operation live for at least another 5 years.

Rejection

Rejection is a normal reaction of the body. When a new organ is transplanted, your body's immune system sees it as a threat and makes antibodies, which can stop the organ working properly.

Immunosuppressant medicines that weaken your immune system are given during and after your transplant and must be taken for life to reduce the risk of your body rejecting the donor bowel.

As well as stopping the donated organ working properly, rejection can sometimes mean that bacteria found in the small bowel can get into your bloodstream and cause a serious widespread infection. 

You'll be closely monitored by the transplant team after surgery to reduce this risk.

There's another rare type of rejection where the immune cells transplanted with the new organ fight against the cells of the host.

This is called graft versus host disease (GvHD). GvHD can happen within a few weeks of a transplant or, less commonly, a few months or even years later.

In some cases where the transplant fails, you may be put on the waiting list again for another transplant.